A MSHA review of the nine incidents has showed three occurred while a crosscut was being turned and a fourth occurred while mining was being conducted adjacent to a crosscut.
In all four accidents, improper operator positioning was a contributing factor. In three of these accidents the victim was located under unsupported roof. In the fourth accident the victim was located in a "no work/travel zone" as defined in that mine's roof control plan.
“The importance of proper operator positioning when remote controlled continuous mining machines are used has long been recognized. However, the recent fatal accidents indicate that increased safety awareness is needed by these machine operators when turning crosscuts,” said MSHA.
Factors such as visibility, dust, equipment crowding, location of ventilation devices and trailing cables also complicate the issue of proper operator positioning while crosscuts are being turned.
From underground observations in numerous mines, MSHA has identified six currently-used best practices which can help to minimize the hazards encountered when crosscuts are turned with remote controlled continuous mining machines.
Use a notch or niche cut. A notch or niche cut is a shallow, triangular-shaped, initial cut (a single miner head in width) taken when turning a crosscut. The notch or niche cut is bolted to provide a buffer between the continuous miner operator and unsupported roof created as the remainder of the crosscut is mined.
Limit the depth of the first cut when turning a crosscut.
Allow the remote controlled continuous miner operator to be positioned up the straight on the inby side of the intersection.
Limit the number of "turned crosscuts", thereby mining most of the crosscuts "head-on".
Install additional roof support at the continuous mining machine operator's projected work location.
Use visual indicators, such as reflective markers, to designate a no work/travel zone commonly referred to as a "Red Zone".
Conduct training and assure that remote control units have safeguards against accidental tram activation.
Ensure emergency stop and operational controls are functional before mining or tramming machine.
De-energize electrical power to machine before servicing or setting bits. De-energize pump motor when making methane checks, extending ventilation devices, or positioning trailing cables.
Use remote control units equipped with the design safeguards recommended in MSHA Program Information Bulletin No. P03-03, "Recommended Design Safeguards for Permissible Remote Controlled Mining Machines.
